Anticoagulants prescribed frequently in atrial fibrillation patients, despite contraindications

Between 2004 and 2015 in the United Kingdom, 38,000 patients with atrial fibrillation (AF) with contraindications to anticoagulant therapy were treated with anticoagulants, according to researchers at the University of Birmingham. They also found that the presence or absence of recorded contraindications did little to influence the decision to prescribe anticoagulants for the prevention of stroke in these patients. They published their results in the latest issue of the British Journal of General Practice.

“These patients are at high risk of stroke and anticoagulant drugs greatly reduce the stroke risk as they make blood less likely to clot,” said lead author Nicola Adderley, MA, MSci (Cantab), MA, MPhil, PhD, MPH, research fellow, Institute of Applied Health Research, University of Birmingham, Edgbaston, Birmingham, United Kingdom. “However, because they reduce blood clotting, patients taking anticoagulant drugs are at risk of bleeding complications. Therefore, safety advice is to avoid anticoagulants in patients who have certain conditions such as a bleeding peptic ulcer, diabetic eye disease, or a previous stroke caused by a bleed.”

Dr. Adderley and colleagues undertook this cross-sectional study to assess the influence of contraindications on anticoagulant prescribing in patients with AF in the UK.

From 2004 to 2015, they conducted 12 sequential cross-sectional analyses of primary care data from 645 general practices in The Health Improvement Network, a large UK database of electronic primary care records. Researchers included all AF patients aged 35 years or older who were registered for at least 1 year. The primary outcome measure was prescription of anticoagulant medication.

Dr. Adderley and colleagues found that over the 12 years studied, the proportion of eligible patients with AF with contraindications prescribed anticoagulants increased from 40.1% (95% CI: 38.3-41.9) to 67.2% (95% CI: 65.6-68.8). Furthermore, the proportion of patients without contraindications who were prescribed anticoagulants increased from 42.1% (95% CI: 41.6-42.6) to 67.7% (95% CI: 67.2-68.1).

In those patients who had a recent history of major bleeding or aneurysm, prescribing rates increased from 44.3% (95% CI: 42.2-46.5) and 34.8% (95% CI: 29.4-40.6), respectively, in 2014, to 71.7% (95% CI: 69.9-73.5) and 63.2% (95% CI: 58.3-67.8) in 2015. This was comparable to rates found in patients without contraindications.

“Our study shows that safety advice seems not to influence the prescribing of anticoagulants. We found that patients considered a safety risk were just as likely to be prescribed the drugs as those without safety risks, and this occurred in every year between 2004 and 2015,” said senior author Professor Tom Marshall, MB ChB, MSc, PhD, MRGP, FFPH, professor of Public Health and Primary Care, Institute of Applied Health Research.

“Because anticoagulants prevent strokes in people with this type of irregular pulse, GPs are encouraged to prescribe more anticoagulants to those who need them. This has been happening and it is good news. But the sting in the tail is that more people who perhaps shouldn’t be on anticoagulants are also taking them: about 38,000 nationally. We need to understand the reasons for this and whether patients might come to any harm,” he added.